The book talks as if modern economists have made a large break from traditional assumptions; many heterodox economists see the two as simply minor modifications of the same approach. In what way is...

The book talks as if modern economists have made a large break from traditional assumptions; many heterodox economists see the two as simply minor modifications of the same approach. In what way is that true? If modern economics focuses on empirical models, does that mean that those aspects of life that cannot be quantified are shortchanged?